1. Field of the Invention
This invention relates generally to hand-held knives. More specifically, the invention relates to a method for improving characteristics of hand-held knife blades.
2. Description of Related Art
When discussing the present invention, the term “knife blade” or “blade” will be most often used to refer to cutting edges of hand-held instruments to which this invention is applicable. It should be understood that the present invention applies to any type of hand-held instrument having a cutting edge where sharpness, the ability to remain sharp, and resistance to chipping are important features of the hand-held cutting edge. Examples of applicable instruments include hunting knives, pocket knives, hatchets, cleavers, axes, scissors, box cutters, craft blades and the like.
Sharpness and the ability to retain a razor sharp edge are two important criteria for a hand-held knife blade. When hand-held knives are used to cut wire, bone, or any other hard or abrasive material, it is understood to be abuse. Abuse often results in the blade of the hand-held knife failing by becoming dull and/or developing chips. A hand-held blade that can withstand abuse and yet retain a sharp edge is a most desired characteristic that has long been sought after by those in the business of manufacturing hand-held knife blades. However, because impact resistance and toughness is inversely related to wear resistance and hardness for most hand-held blade materials, different hand-held knife blades are typically required for impact applications, such as chopping through bone and hard wood without chipping, and sharpness applications, such as cutting through animal flesh, and the like.
Certain products such as large cleavers and hatchets have been specifically designed to withstand the impact of cutting through hard dried wood and especially bone without the edge chipping. However, conventionally, increased impact toughness means lower RC hardness as compared to the higher RC values of other hand-held knife blades. As a result, the ability to maintain a sharp edge (referred to hereinafter as edge retention) is compromised. A technique has been developed to test several different types of steel at different “Rockwell” or RC hardness measurements until a happy medium is found between “good” edge retention, where there is no dulling of the blade, and the prevention of edge chipping.
For example, a conventional D2 steel hand-held cleaver, such as a Brown Bear™ Cleaver sold by Knives of Alaska, is designed to consistently cut through bone without chipping. However, when a rope is repeatedly cut with the hand-held cleaver, the edge retention is typically not up to par with harder hand-held knife blades, such as a Jaeger™ Boning knife also sold by Knives of Alaska. Similarly, harder hand-held knife blades that offer increased edge retention in low impact cutting applications typically experience edge chipping when used to cut or chop through harder material such as hard wood and bone due to the increased brittleness of the hand-held blade.
Ideally, a hand-held blade would be able to withstand abrasive cutting and retain a sharp edge, yet be able to withstand the high impact necessary to chop through solid bone, hard dried wood, etc., without the edge chipping or fracturing.
Accordingly, what is desired is a hand-held knife blade or cutting edge for a hand-held hatchet or other hand cutting instrument that can withstand the high impact of chopping or cutting through hard materials, and still provide superior edge retention.